Constant current circuit of gas shielded welding machine

Abstract

The utility model discloses a constant current circuit of a gas shielded welding machine, which belongs to the technical field of inverter welding power supplies and comprises a welding machine power supply output sampling network, a first-stage signal processing network and a second-stage signal processing network which are connected in sequence. The actual current and the given current are calculated through the first-stage signal processing network, the calculation result and the motor voltage signal are calculated through the second-stage signal processing network, a PWM pulse width control signal is obtained, then the rotating speed of the motor is controlled, the rotating speed equal to the given current is obtained, and the purpose of constant current is achieved. According to the constant-speed or constant-speed wire feeding circuit, the problem that when an existing constant-speed or constant-speed wire feeding circuit encounters a workpiece with a non-flat surface or a special-shaped special workpiece, the distance between a welding gun and the surface of the workpiece has the phenomenon that the arc length of an electric arc is inconsistent, so that the magnitude of current changes along with the arc length, and the depth of welding penetration is inconsistent is solved.

Description

Technical Field

[0001] The utility model belongs to the technical field of inverter welding power supply, and in particular relates to a constant current circuit of a gas shielded welding machine. Background Art

[0002] The welding power supply is the core part of the welding equipment. Its function is to provide the electrical energy required for welding, including current and voltage, to generate the welding arc, heat and melt the workpiece and filler material, and realize the connection between metals. The arc should not be too long during the welding process, otherwise, the arc burning is unstable, the metal spatter increases, and the weld will produce pores due to the invasion of air. And the size of the welding current has a great influence on the welding quality and welding productivity. The welding current mainly affects the size of the penetration. If the current is too small, the arc is unstable, the penetration is small, and it is easy to cause defects such as incomplete penetration and slag inclusion, and the productivity is low. If the current is too large, the weld is prone to defects such as undercut and burn-through, and spatter is caused.

[0003] At present, the welding power supplies used in the field of gas shielded welding power supply are basically uniform or constant speed wire feeding circuits. As the surface of some workpieces is not very flat or there are special workpieces with irregular shapes, the distance between the welding gun and the workpiece surface will result in inconsistent arc lengths. The current size will also change with the length of the arc, which directly affects the inconsistent depth of welding penetration and cannot meet the requirements of existing welding processes. Utility Model Content

[0004] The utility model provides a constant current circuit for a gas shielded welding machine, which solves the problem that when the existing constant speed or constant speed wire feeding circuit encounters a workpiece surface that is not very flat or a special workpiece with an irregular shape, the arc length will be inconsistent due to the distance between the welding gun and the workpiece surface, resulting in the current size changing with the arc length, causing the depth of welding penetration to be inconsistent.

[0005] In order to solve the above technical problems, the technical solution adopted by the utility model is:

[0006] The utility model provides a constant current circuit of a gas shielded welding machine, comprising a welding machine power supply output sampling network, a first-level signal processing network and a second-level signal processing network which are connected in sequence;

[0007] The output end of the welding machine power supply output sampling network is connected to the first input end of the first-level signal processing network; the output end of the first-level signal processing network is connected to the first input end of the second-level signal processing network; the input end of the welding machine power supply output sampling network, the second input end of the first-level signal processing network and the second input end of the second-level signal processing network serve as the input end of the constant current circuit; the output end of the second-level signal processing network serves as the output end of the constant current circuit.

[0008] Further, the welding machine power supply output sampling network includes an amplifier U1A of model TL084, a grounding capacitor C1, a grounding capacitor C2, a grounding capacitor C6, a grounding resistor R2 and a resistor R3;

[0009] The output end of the amplifier U1A is connected to the negative input end of the amplifier U1A and serves as the output end of the welding machine power output sampling network; the positive input end of the amplifier U1A is respectively connected to the grounding resistor R2, the grounding capacitor C2 and one end of the resistor R3; the other end of the resistor R3 serves as the input end of the welding machine power output sampling network and inputs the welding machine output current; the negative power supply end of the amplifier U1A is respectively connected to the grounding capacitor C6 and the -15V voltage; the positive power supply end of the amplifier U1A is respectively connected to the grounding capacitor C1 and the +15V voltage.

[0010] Further, the first-stage signal processing network includes an amplifier U1B of model TL084, a resistor R1, a grounding resistor R4, a resistor R5, a resistor R6, a resistor R12, a grounding capacitor C3 and a capacitor C4;

[0011] The negative input terminal of the amplifier U1B is respectively connected to one end of the resistor R5, one end of the capacitor C4, the grounding capacitor C3, the grounding resistor R4 and one end of the resistor R1; the output terminal of the amplifier U1B is respectively connected to the other end of the resistor R5 and one end of the resistor R6, and serves as the output terminal of the first-level signal processing network; the other end of the capacitor C4 is connected to the other end of the resistor R6; the other end of the resistor R1 serves as the first input terminal of the first-level signal processing network; the positive input terminal of the amplifier U1B is connected to one end of the resistor R12; the other end of the resistor R12 serves as the second input terminal of the first-level signal processing network, and inputs the current given signal.

[0012] Further, the second-stage signal processing network includes an amplifier U1C of model TL084, a resistor R7, a resistor R8, a resistor R9, a resistor R10, a resistor R11, a capacitor C5 and a diode V1;

[0013] The negative input terminal of the amplifier U1C is respectively connected to one end of the resistor R7, one end of the resistor R9, one end of the resistor R8, the positive electrode of the diode V1 and one end of the capacitor C5; the other end of the resistor R7 serves as the first input terminal of the second-level signal processing network; the other end of the resistor R8 serves as the second input terminal of the second-level signal processing network, and inputs the M-Vfb voltage signal; the output terminal of the amplifier U1C is respectively connected to the other end of the resistor R9, one end of the resistor R11, the negative electrode of the diode V1 and one end of the resistor R10; the other end of the capacitor C5 is connected to the other end of the resistor R10; the other end of the resistor R11 serves as the output terminal of the second-level signal processing network, and outputs the PWM pulse width control signal; the positive input terminal of the amplifier U1C is grounded.

[0014] The beneficial effects of the utility model are as follows: (1) the actual current output by the welding machine is sampled through the welding machine power supply output sampling network, and is calculated with the given current, and the calculated result is further calculated with the motor voltage signal to obtain a PWM pulse width control signal, and the motor speed is controlled by the PWM pulse width control signal, so as to obtain a speed equal to the given current, thereby achieving the purpose of constant current, and solving the problem that when the existing constant speed or constant speed wire feeding circuit encounters a workpiece surface that is not very flat or a special workpiece with an irregular shape, there is a problem that the arc length is inconsistent due to the distance between the welding gun and the workpiece surface, resulting in the current size changing with the length of the arc, making the depth of welding penetration inconsistent.

[0015] (2) The analog circuit adopted by the utility model has a simple circuit structure, is easy to operate and has low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The utility model is a block diagram of the constant current circuit of the gas shielded welding machine.

[0017] Figure 2 This is the circuit diagram of the welding machine power output sampling network of the utility model.

[0018] Figure 3 This is a circuit diagram of the first-level signal processing network of the utility model.

[0019] Figure 4 This is a circuit diagram of the second-level signal processing network of the utility model. DETAILED DESCRIPTION

[0020] Those skilled in the art will appreciate that the embodiments described herein are intended to help readers understand the principles of the present invention, and should be understood that the protection scope of the present invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific variations and combinations based on the technical inspirations disclosed in the present invention without departing from the essence of the present invention, and these variations and combinations are still within the protection scope of the present invention.

[0021] Example

[0022] like Figure 1 As shown, the utility model provides a constant current circuit of a gas shielded welding machine, comprising a welding machine power supply output sampling network, a first-level signal processing network and a second-level signal processing network connected in sequence;

[0023] The output end of the welding machine power supply output sampling network is connected to the first input end of the first-level signal processing network; the output end of the first-level signal processing network is connected to the first input end of the second-level signal processing network; the input end of the welding machine power supply output sampling network, the second input end of the first-level signal processing network and the second input end of the second-level signal processing network serve as the input end of the constant current circuit; the output end of the second-level signal processing network serves as the output end of the constant current circuit.

[0024] like Figure 2 As shown, the welding machine power supply output sampling network includes an amplifier U1A of model TL084, a grounding capacitor C1, a grounding capacitor C2, a grounding capacitor C6, a grounding resistor R2 and a resistor R3;

[0025] The output end of the amplifier U1A is connected to the negative input end of the amplifier U1A and serves as the output end of the welding machine power output sampling network; the positive input end of the amplifier U1A is respectively connected to the grounding resistor R2, the grounding capacitor C2 and one end of the resistor R3; the other end of the resistor R3 serves as the input end of the welding machine power output sampling network and inputs the welding machine output current; the negative power supply end of the amplifier U1A is respectively connected to the grounding capacitor C6 and the -15V voltage; the positive power supply end of the amplifier U1A is respectively connected to the grounding capacitor C1 and the +15V voltage.

[0026] like Figure 3 As shown, the first-stage signal processing network includes an amplifier U1B of model TL084, a resistor R1, a grounding resistor R4, a resistor R5, a resistor R6, a resistor R12, a grounding capacitor C3 and a capacitor C4;

[0027] The negative input terminal of the amplifier U1B is respectively connected to one end of the resistor R5, one end of the capacitor C4, the grounding capacitor C3, the grounding resistor R4 and one end of the resistor R1; the output terminal of the amplifier U1B is respectively connected to the other end of the resistor R5 and one end of the resistor R6, and serves as the output terminal of the first-level signal processing network; the other end of the capacitor C4 is connected to the other end of the resistor R6; the other end of the resistor R1 serves as the first input terminal of the first-level signal processing network; the positive input terminal of the amplifier U1B is connected to one end of the resistor R12; the other end of the resistor R12 serves as the second input terminal of the first-level signal processing network, and inputs the current given signal.

[0028] like Figure 4 As shown, the second-stage signal processing network includes an amplifier U1C of model TL084, a resistor R7, a resistor R8, a resistor R9, a resistor R10, a resistor R11, a capacitor C5 and a diode V1;

[0029] The negative input terminal of the amplifier U1C is respectively connected to one end of the resistor R7, one end of the resistor R9, one end of the resistor R8, the positive electrode of the diode V1 and one end of the capacitor C5; the other end of the resistor R7 serves as the first input terminal of the second-level signal processing network; the other end of the resistor R8 serves as the second input terminal of the second-level signal processing network, and inputs the M-Vfb voltage signal; the output terminal of the amplifier U1C is respectively connected to the other end of the resistor R9, one end of the resistor R11, the negative electrode of the diode V1 and one end of the resistor R10; the other end of the capacitor C5 is connected to the other end of the resistor R10; the other end of the resistor R11 serves as the output terminal of the second-level signal processing network, and outputs the PWM pulse width control signal; the positive input terminal of the amplifier U1C is grounded.

[0030] The working principle of the utility model is as follows: the actual current output by the welding machine is sampled through the welding machine power supply output sampling network, and the first output signal is obtained by calculating with the current setting through the first-level signal processing network, and the first output signal is input into the second-level signal processing network. At the same time, the voltage signal of the motor voltage sampling, that is, the M-Vfb voltage signal, is input into the second-level signal processing network, and the second-level signal processing network calculates the first output signal and the M-Vfb voltage signal to obtain the second output signal, that is, the PWM pulse width control signal, and the motor speed is controlled by the PWM pulse width control signal, so as to obtain a speed equal to the given current, and thus achieve the purpose of constant current.

[0031] In this embodiment, when the arc becomes longer, the current output of the power supply will become smaller, which is inconsistent with the current given value. The current signal value returned by the actual current sampling of the power supply is calculated, and the data of the output control signal will become larger, and the pulse width of the PWM control will become wider. At this time, the speed of the wire feeding motor will become faster. When the current signal returned by the actual current sampling of the power supply is equal to the motor speed, the PWM pulse width will stop widening, and the speed of the wire feeding motor will stop increasing. At this time, the welding machine current is equal to the motor speed. When the arc length of the arc becomes shorter, the welding machine current will become larger, which is inconsistent with the motor speed. The current signal returned by the actual current sampling of the power supply is calculated with the current given value, and the data of the output control signal will become smaller, and the pulse width of the PWM control will become narrower, and the speed of the wire feeding motor will slow down. When the current signal returned by the actual current sampling is equal to the current given value, the PWM pulse width will stop narrowing, and the speed of the wire feeding motor will stop slowing down. At this time, the welding machine current is equal to the motor speed.

[0032] Therefore, the circuit of the utility model has the characteristics of stable current and voltage, and can keep the weld penetration consistent even when the distance between the welding gun and the workpiece changes during the welding process of special workpieces, thereby greatly improving the process control and meeting the requirements of the welding process of special workpieces. The power supply will be widely used in the machinery, aviation, chemical, petroleum, electric power and automobile industries, and the market demand is huge.

Claims

1. A constant current circuit for a gas shielded welding machine, characterized in that: It includes a welding machine power supply output sampling network, a first-level signal processing network and a second-level signal processing network which are connected in sequence; The output end of the welding machine power supply output sampling network is connected to the first input end of the first-level signal processing network; the output end of the first-level signal processing network is connected to the first input end of the second-level signal processing network; the input end of the welding machine power supply output sampling network, the second input end of the first-level signal processing network and the second input end of the second-level signal processing network serve as the input end of the constant current circuit; the output end of the second-level signal processing network serves as the output end of the constant current circuit.

2. The constant current circuit of the gas shielded welding machine according to claim 1, characterized in that: The welding machine power supply output sampling network includes an amplifier U1A of model TL084, a grounding capacitor C1, a grounding capacitor C2, a grounding capacitor C6, a grounding resistor R2 and a resistor R3; The output end of the amplifier U1A is connected to the negative input end of the amplifier U1A and serves as the output end of the welding machine power output sampling network; the positive input end of the amplifier U1A is respectively connected to the grounding resistor R2, the grounding capacitor C2 and one end of the resistor R3; the other end of the resistor R3 serves as the input end of the welding machine power output sampling network and inputs the welding machine output current; the negative power supply end of the amplifier U1A is respectively connected to the grounding capacitor C6 and the -15V voltage; the positive power supply end of the amplifier U1A is respectively connected to the grounding capacitor C1 and the +15V voltage.

3. The constant current circuit of the gas shielded welding machine according to claim 1, characterized in that: The first-stage signal processing network includes an amplifier U1B of model TL084, a resistor R1, a grounding resistor R4, a resistor R5, a resistor R6, a resistor R12, a grounding capacitor C3 and a capacitor C4; The negative input terminal of the amplifier U1B is respectively connected to one end of the resistor R5, one end of the capacitor C4, the grounding capacitor C3, the grounding resistor R4 and one end of the resistor R1; the output terminal of the amplifier U1B is respectively connected to the other end of the resistor R5 and one end of the resistor R6, and serves as the output terminal of the first-level signal processing network; the other end of the capacitor C4 is connected to the other end of the resistor R6; the other end of the resistor R1 serves as the first input terminal of the first-level signal processing network; the positive input terminal of the amplifier U1B is connected to one end of the resistor R12; the other end of the resistor R12 serves as the second input terminal of the first-level signal processing network, and inputs the current given signal.

4. The constant current circuit of the gas shielded welding machine according to claim 1, characterized in that: The second-stage signal processing network includes an amplifier U1C of model TL084, a resistor R7, a resistor R8, a resistor R9, a resistor R10, a resistor R11, a capacitor C5 and a diode V1; The negative input terminal of the amplifier U1C is respectively connected to one end of the resistor R7, one end of the resistor R9, one end of the resistor R8, the positive electrode of the diode V1 and one end of the capacitor C5; the other end of the resistor R7 serves as the first input terminal of the second-level signal processing network; the other end of the resistor R8 serves as the second input terminal of the second-level signal processing network, and inputs the M-Vfb voltage signal; the output terminal of the amplifier U1C is respectively connected to the other end of the resistor R9, one end of the resistor R11, the negative electrode of the diode V1 and one end of the resistor R10; the other end of the capacitor C5 is connected to the other end of the resistor R10; the other end of the resistor R11 serves as the output terminal of the second-level signal processing network, and outputs the PWM pulse width control signal; the positive input terminal of the amplifier U1C is grounded.

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